The invention relates to a steering system for road vehicles.
In conventional vehicle steering systems, the steering wheel provided as a steering means is mechanically connected to the steered vehicle wheels, i.e. the steering wheel and the steered vehicle wheels are mechanically positively coupled to one another. A mechanical positive coupling of this kind has so far been a legal requirement on conventional road vehicles.
For the actuation of wing flaps and control surfaces on aircraft however, arrangements are known with no mechanical positive coupling whatsoever between the rudder or the wing flaps on the one hand, and the associated control means on the other hand. Rather, the control surfaces or wing flaps are functionally connected to the corresponding control means via an electronic control path, i.e. the control means specifies a desired position value, in accordance with which the control surfaces or wing flaps are then adjusted by means of correspondingly controlled motorized actuating units. This concept, which is also referred to as "fly by wire", is now so reliable that it is used even in passenger aircraft.
Also in vehicle steering systems, comparable systems are now being developed, wherein the steering control means, that is, the steering wheel operates a desired-value transmitter, and a motorised actuating unit controlled as a function of the desired value performs the steering of the steered vehicle wheels. Since there is no positive coupling between the steered vehicle wheels and the steering control means or steering wheel, a system response force which can be felt at the steering means or steering wheel must be artificially generated by means of a hand-force generator which is operatively connected to the steering means or steering wheel.
It is accordingly the object of the invention to provide a simple and reliable control concept for generating the reaction-force which is felt by the vehicle operator.